SQL column
Summary of SQL basics
SQL advanced knowledge summary
Preface
Recently, many friends are confused about database learning. In fact, the editor also came here before. It took two years to enter the database development road. From the beginning of ignorance to the present It's OK. There is no shortcut. Those who tell you that there is a shortcut do not want to fool the money in your pocket, or they don't know how to blow water with you there. Below are some of my personal opinions, I hope it will be helpful to you~
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I have always wanted to write about how to learn SQL more effectively, but I have not had much time. Let’s talk about the upgrade path of SQL today.
The following are some of the author's learning methods and processes, novice students can learn from one or two.
I learned about the database during my studies. At that time, our lecturer was very easy to understand, and I soon liked this course "Introduction to Databases". It was the first time I came into contact with the database, especially the exercises after class. Deepen the consolidation of basic knowledge. This course also teaches a lot of database principles, especially set theory and three-paradigm. I personally feel that if I have time, I should read more of such books, the combination of theory and operation will be more effective.
After working, I first came into contact with SQL Server. I found the book "SQL Server From Entry to Proficiency" on the Internet and read it. The graphical interface of SQL Server is very suitable for novice students. The above are all basic Operations, such as adding, deleting, updating, viewing, backing up, and restoring can all be done with the right mouse button. I think this book is pretty good. Maybe it's because I have some foundation during my studies, so I don't seem to be stressed. At that time, I used the SQL Server2008R2 version, which was a relatively full-featured version. The latest 2017 version also added a lot of content, but these functions are basically not available for novice students.
Later, I changed my job and started to come into contact with Oracle. Compared to SQL Sever, this is a bit more complicated, except for the structure inside, but if it is only used for programming, there is no pressure at all. Because mainstream database software supports unified ANSI/ISO standards, some commonly used writing methods are common, such as:
SELECT * FROM TAB;
This paragraph can be executed in SQL Sever, Oracle and Mysql to be mentioned later. They will not be written differently because of the difference in software. So if you are a beginner in Oracle and Mysql, don't worry about the big difference between these software. Although they are almost the same, I found the video tutorial "Playing with Oracle in 21 Days" by Mr. Han Shunping, and the lecture is still relatively good. I read it twice before and after. Some of the operations on the database are more interesting, suitable for people who want to be a DBA, and then I also read "Oracle From Entry to Proficiency" by Qian Qianyi, which are more suitable for novices. I also recommend it to colleagues and friends who want to work on the database. The response is good. It can be used not only as a tutorial but also as a reference book.
Here is an episode. When I was working, a colleague was doing an audit. He often asked me to extract data. Then he became a friend once and again. He always wanted me to teach him how to learn SQL. I recommended a few books to him. I said you go back from get off work and follow the instructions in this book. If you don’t understand, please ask me at any time. If you don’t understand, please Baidu first. If you don’t understand, I’ll help you solve it. I have mastered the basic operations and writing of SQL in a month. I think this progress is already fast. The main reason is that he is more insistent, because he feels that the audit is not what he wants to do. After a period of training, his salary has doubled compared to when he did the audit.
The company I went to later used Mysql. Because of the SQL foundation, it was relatively quick to get started, but some special writing methods still need to be studied on Baidu. The biggest feeling is that the format function and date function inside are similar to other databases. The big difference is that there is also a certain difference in the way the trigger is written. The company uses Alibaba Cloud servers. During this period, I often encountered slow query problems. So I found several books on Mysql performance optimization. One of them, "High-performance Mysql", is better and contains some optimization methods. Tried and tested. Especially when you understand some of the principles, optimization is a matter of course. These have always been boasted by some bigwigs, but they are indeed qualified to brag, because they can make a query that can take as little as tens of seconds and as long as a few hours. Optimizing to milliseconds or a few seconds, you can imagine how much efficiency this will improve. Because I have encountered such a problem myself, and I have practiced it according to other people's optimization methods and it is indeed effective. So far, the author only knows a little bit about performance optimization, and it is not a great god.
The only thing you can do is to continuously absorb knowledge to enrich your experience and strengthen your skills to make your work less tiring. Of course, these are all things to follow, just tell novice friends if you choose this line, please go on bravely, if you are not afraid of difficulties, you are afraid that you will not solve them and stay in place.
The above are some of my personal work and learning experiences that I have shared, I hope to help everyone~